Parking device of vehicle

ABSTRACT

A parking device for vehicles in which when an engine is brought into a halt, a clutch is disconnected and the revolution of an input shaft of a transmission cannot be controlled by frictional force of the engine, the parking device comprising a parking gear provided on the input shaft, a parking lock mechanism which selectively engages with the parking gear, a change lever which instructs a gear position of the transmission and is mechanically coupled to the parking lock mechanism, a speed-change actuator for shifting the transmission to each gear position, wherein the parking device further comprises a neutral position detection means of the change lever, a parking operation detection means arranged in an operation passage from the neutral position to a parking position, of the change lever, a vehicle speed sensor, a control means; and, when the operation of the change lever is detected by the parking operation detection means, the control means sends a control signal to the speed-change actuator to bring the transmission into engagement with a gear position that corresponds to the traveling speed of the vehicle.

TECHNICAL FIELD

The present invention relates to a parking device for vehicles in whichwhen an engine is brought into a halt, a clutch is disconnected andhence, the revolution of an input shaft of a transmission cannot becontrolled by a frictional force of the engine.

BACKGROUND ART

In a vehicle mounting an automatic transmission that comprises a fluidtransmission, the vehicle has a structure that a hydraulic pressure isproduced by a hydraulic pump driven by an engine, and a multiple-discclutch is engaged by the hydraulic pressure to secure a gear position.When the engine is brought into a halt, therefore, no hydraulic pressurecan be produced and consequently, the transmission automatically becomesa neutral state at the time of shutdown of the engine. Therefore, thevehicle mounting the automatic transmission that comprises a fluidtransmission is not capable of limiting the rotation of the wheels byutilizing the frictional force of the engine. Accordingly, the vehiclemounting the automatic transmission that is a fluid transmission has aparking gear that is provided on the output shaft of the transmissionand is equipped with a parking lock mechanism, which selectively engageswith the above parking gear, so that the parking lock mechanism isengaged with the parking gear at the time of parking. When the parkinggear provided on the output shaft of the transmission is locked,however, a maximum output torque of the transmission acts on the parkinglock mechanism creating a condition, which is very disadvantageous fromthe standpoint of strength. In the medium- to heavy-sized trucksmounting the automatic transmissions, therefore, the parking lockmechanism is not established from the standpoint of strength and hence,the parking lock mechanism is hardly furnished.

Meanwhile, in the vehicles using a parallel shaft gear type transmissionand using a hydraulic multiple-disc clutch or an electromagnetic powderclutch, too, the clutch is disconnected when the engine is brought intoa halt and hence, the rotation of the wheels cannot be limited byutilizing the frictional force of the engine. In the vehicles of thistype, too, therefore, it can be contrived to provide the output shaft ofthe transmission with a parking gear and to lock the parking gear at thetime of parking. In the medium- to heavy-sized trucks, however, theparking lock mechanism is not established from the standpoint ofstrength as described above. To solve this problem, JP-A 2000-264178discloses a parking device for a vehicle having a parking gear providedon the input shaft of the transmission so that the parking gear islocked at the time of parking.

However, in the parking device for vehicles in which the input shaft ofthe transmission is provided with a parking gear so that is locked atthe time of parking, as is described in the above publication, thetransmission must be brought into engagement with a predetermined gearposition prior to locking the parking gear. When the change lever isoperated to the parking position while the vehicle is traveling,however, it is operated to the parking position via the neutralposition. Therefore, the clutch is disconnected and the transmissionremains in the neutral state. Namely, in the device in which the parkinglock mechanism is mechanically coupled to the change lever, no drivingforce acts on the input shaft of the transmission and hence, the parkinglock mechanism works if the change lever is shifted to the parkingposition. As a result, the input shaft is locked making it difficult tobring the transmission into engagement with a predetermined gearposition. Even when the change lever is operated to the parking positionat the time of parking, therefore, the transmission remains in theneutral state arousing a problem in that the parking lock function doesnot work.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide a parkingdevice for vehicles, which is so designed as to bring the transmissioninto engagement with any gear position even when the change lever isshifted to the parking position while the vehicle is traveling.

In order to achieve the above object, the present invention is toprovide a parking device for vehicles in which when the engine isbrought into a halt, a clutch is disconnected and the revolution of aninput shaft of a transmission cannot be controlled by frictional forceof the engine, the parking device comprising a parking gear provided onthe input shaft, a parking lock mechanism which selectively engages withthe parking gear, a change lever which instructs a gear position of thetransmission and is mechanically coupled to the parking lock mechanism,and a speed-change actuator for shifting the transmission to each gearposition; wherein

said parking device further comprises a neutral position detection meansarranged at a neutral position of the change lever, a parking operationdetection means arranged in an operation passage of the change leverfrom the neutral position to a parking position, a vehicle speed sensorfor detecting the traveling speed of the vehicle, and a control meansfor controlling the speed-change actuator and the clutch based ondetection signals from the neutral position detection means, the parkingoperation detection means and the vehicle speed sensor; and

when the operation of the change lever is detected by the parkingoperation detection means, the control means sends a control signal tothe speed-change actuator based on a detection signal from the vehiclespeed sensor to bring the transmission into engagement with a gearposition that corresponds to the traveling speed of the vehicle.

Provision is further made of a limiting means for limiting theengagement of the parking lock mechanism with the parking gear, and thecontrol means temporarily operates the limiting means based on adetection signal from the parking operation detection means when theoperation of the change lever is confirmed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating the constitution of aparking device for vehicles according to the present invention;

FIG. 2 is a flowchart illustrating the procedure of operation of acontrol means constituting the parking device for vehicles according tothe present invention; and

FIG. 3 is a diagram illustrating an operation pattern of a change leverconstituting the parking device for vehicles according to the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of a parking device for vehicles constitutedaccording to the present invention will now be described in furtherdetail with reference to the accompanying drawings.

FIG. 1 is a view schematically illustrating the constitution of aparking device for vehicles according to the present invention. A driveshaft 2 driven by an engine (not shown) such as an internal combustionengine and an input shaft 31 of a transmission 3 are arranged on thesame axis. A hydraulic multiple-disc clutch 4 is arranged between thedrive shaft 2 and the input shaft 31. The hydraulic multiple-disc clutch4 may be constituted by a clutch outer 41 mounted on the drive shaft 2and a clutch inner 42 mounted on the input shaft 31 in a customarymanner. The hydraulic multiple-disc clutch 4 is connected, through apassage 45, to a hydraulic pump (not shown) driven by the engine, and anelectromagnetic change-over valve 46 (V1) is disposed in the passage 45.The transmission 3 is a known parallel shaft gear type transmission, andis so constituted as to be brought into engagement with each gearposition by a speed-change actuator 5. The speed-change actuator 5 maybe the known one comprising a select actuator 51 and a shift actuator 52which are constituted, for example, by electric motors, and is actuatedby a speed-change instruction signal sent from a control means that willbe described later.

A parking gear 6 is mounted on the input shaft 31 of the transmission 3.The parking gear 6 is so designed as to selectively engage with aparking lock mechanism 7. The parking lock mechanism 7 has an engagingmember 71 that is arranged facing the outer periphery of the parkinggear 6 and is supported by a casing 32 of the transmission 3 so as toslide in an up-and-down direction in the drawing. The engaging member 71has, at a lower end thereof in the drawing, teeth 711 to engage with theparking gear 6, and has, at an upper end thereof, an inclinedto-be-operated surface 712. The inclined to-be-operated surface 712 isinserted in a housing 72 arranged on the upper side of the casing 32.The thus formed engaging member 71 is urged upward in the drawing due toa coil spring 73 arranged relative to the casing 32. In the housing 72,an operation member 74 that operates the engaging member 71 is arrangedso as to be allowed to slide in the right-and-left direction in thedrawing. The operation member 74 has an inclined operation surface 741that engages with the inclined to-be-operated surface 712 of theengaging member 74, and has a through-hole 742 penetrating through inthe right-and-left direction in the drawing. An operation rod 75 isslidably inserted in the through-hole 742 of the thus formed operationmember 74. A stopper 751 is mounted on the right end of the operationrod 75 in the drawing. Further, a spring receiver 752 is provided on theoperation rod 75 on the left side of the operation member 74 in thedrawing. A coil spring 76 is arranged between the spring receiver 752and the operation member 74. A push-pull cable 78 operated by a changelever 77 is coupled to the left end of the operation rod 75 in thedrawing. Therefore, when the change lever 77 is operated in a directionindicated by an arrow in the drawing, the operation rod 75 moves towardthe right in the drawing via the push-pull cable 78 and hence, theoperation member 74 moves toward the right in the drawing via the coilspring 76. When the operation member 74 moves toward the right in thedrawing, the engaging member 71 moves downward in the drawing againstthe spring force of the coil spring 73 due to the engaging actionbetween the inclined operation surface 741 of the operation member 74and the inclined to-be-operated surface 712 of the engaging member 71,whereby the teeth 711 formed at the lower end thereof is brought intoengagement with the parking gear 6.

In the illustrated embodiment, the above change lever 77 is soconstituted as to be operated to the neutral position (N), driveposition (D), reverse position (R) and parking position (P) inconformity with the operation pattern that is illustrated. Detectionmeans are each provided at therespectiveoperationpositionsofthechangelever77. Namely, a neutralposition detection means 81 (SW1) is provided at the neutral position(N), a drive position detection means 82 (SW2) is provided at the driveposition (D), a reverse position detection means 83 (SW3) is provided atthe reverse position (R), and a parking position detection means 84(SW4) is provided at the parking position (P) respectively. In theillustrated embodiment, a parking operation detection means 85 (SW5) isprovided in the operation passage from the neutral position (N) to theparking position (P), i.e., between the neutral position (N) and theparking position (P). These detection means send their detection signalsto the control means that will be described later.

In the illustrated embodiment, there is further provided anelectromagnetic solenoid 9 (SOL) which serves as a parking lock limitingmeans for temporarily limiting the movement of the operation member 74that constitutes the parking lock mechanism 7 even in a state where thechange lever 77 has been operated to the parking position (P). Theelectromagnetic solenoid 9 (SOL) comprises a cylindrical casing 91, afixed yoke 92 that is made of a magnetic material and is mounted on anend on the side of the housing 72 of the casing 91, a moving yoke 93that comes in contact with, and separates away from, the fixed yoke 92,a push rod 94 that is made of a nonmagnetic material and mounted, at itsone end, on the moving yoke 93, an electromagnetic coil 95 arrangedsurrounding the fixed yoke 92 and the moving yoke 93, and a cover member96 that is mounted on the other end of the casing 91 and covers themoving yoke 93. In the thus constituted electromagnetic solenoid 9(SOL), an end of the push rod 94 penetrates through the housing 72 andfaces the right end surface of the operation member 74 in the drawing.When the electromagnetic coil 95 is energized in the thus constitutedelectromagnetic solenoid 9 (SOL), the moving yoke 93 is attracted by thefixed yoke 92, and the push rod 94 mounted on the moving yoke 93 movestoward the left in the drawing to limit the operation member 74 frommoving toward the right in the drawing.

The parking device of the illustrated embodiment has a control means 10.The control means 10 is constituted by a microcomputer, and has acentral processing unit (CPU) for executing an arithmetic processingaccording to a control program, a read-only memory (ROM) for storing thecontrol program, a read-write random access memory (RAM) for storing theoperated results, a timer and the like. The control means 10 receivesdetection signals from the neutral position detection means 81 (SW1),drive position detection means 82 (SW2), reverse position detectionmeans 83 (SW3), parking position detection means 84 (SW4), parkingoperation detection means 85 (SW5), a vehicle speed sensor 11 fordetecting a traveling speed of the vehicle, and an accelerator sensor 12for detecting the amount of the accelerator pedal (not shown) depressed.The control means 10 sends control signals to the select actuator 51 andthe shift actuator 52 that constitute the speed-change actuator 5 (ACT),to the electromagnetic change-over valve 56 (V1) and to theelectromagnetic solenoid 9 (SOL), and the like.

The parking device of the illustrated embodiment is constituted asdescribed above. Described below is the operation thereof.

When the change lever 77 is operated to the neutral position (N), thecontrol means 10 sends a control signal to the select actuator 51 andthe shift actuator 52 constituting the speed-change actuator 5 (ACT)based on a detection signal from the neutral position detection means 81(SW1) to place the transmission 3 in the neutral state. When the changelever 77 is positioned to the drive position (D), the control means 10executes an automatic speed-change control based on a detection signalfrom the drive position detection means 82 (SW2). That is, the controlmeans 10 determines a target gear position based on the detectionsignals from the vehicle speed sensor 11 and the accelerator sensor 12,and sends control signals to the select actuator 51 and to the shiftactuator 52 so that the transmission is brought into engagement with thetarget gear position that has been determined. Next, when the changelever 77 is positioned to the reverse position (R), the control means 10sends control signals to the select actuator 51 and to the shiftactuator 52 based on a detection signal from the reverse positiondetection means 83 (SW3) so that the transmission 3 is brought intoengagement with the reverse gear position.

Next, described blow is a case when the change lever 77 is operatedtoward the parking position (P) while the vehicle is traveling withreference also to a flowchart of FIG. 2.

When the change lever 77 is operated toward the parking position (P) ,asthe parking operation detection means 85 (SW5) is disposed in thepassage on the way to the parking position (P), the control means 10 atstep S1 checks whether the parking operation detection means 85 (SW5) isturned on. When the parking operation detection means 85 (SW5) has notbeen turned on at step S1, the control means 10 judges that the changelever 77 is not operated toward the parking position (P), and ends theroutine. When the parking operation detection means 85 (SW5) has beenturned on at step S1, the control means 10 judges that the change lever77 is operated toward the parking position (P), and proceeds to step S2to check whether the transmission 3 is in the neutral state. In the casewhere the change lever 77 has an operation pattern shown in theembodiment, when the change lever 77 is operated to the parking position(P) during traveling of the vehicle, it passes the neutral position (N).Based on a detection signal from the neutral position detection means 81(SW1), therefore, the control means 10 sends control signals to theselect actuator 51 and the shift actuator 52 constituting thespeed-change actuator 5 (ACT), so that the transmission 3 should havebeen placed in the neutral state. For caution's sake, however, thecontrol means 10 checks at step S2 to make sure the neutral state. Theneutral state of the transmission 3 is judged based on a signal fromneutral position detection means (not shown) provided in the shiftactuator 52.

When the transmission 3 is not in the neutral state at step S2, it meansthat the transmission 3 is engaged with any one of the gear positions,and the routine ends. When the transmission 3 is in the neutral state atstep S2, the control means 10 proceeds to step S3 and produces a controlsignal to energize (turn on) the electromagnetic coil 95 of theelectromagnetic solenoid 9 (SOL) thereby to operate the electromagneticsolenoid 9 (SOL). As a result, the operation member 74 is limited frommoving toward the right in the drawing as described above.

Next, the control means 10 proceeds to step S4 to de-energize (turn off)the electromagnetic change-over valve 46 (V1) and to disconnect thetransmission of power of the hydraulic multiple-disc clutch 4. Thecontrol means 10, then, proceeds to step S5 and sends control signals tothe select actuator 51 and to the shift actuator 52 constituting thespeed-change actuator 5 (ACT), so that the transmission 3 is broughtinto engagement with a gear position that corresponds to the travelingspeed of the vehicle. As a result, the transmission 3 is brought intoengagement with a gear position that corresponds to the traveling speedof the vehicle. During this operation, the change lever 77 arrives atthe parking position (P). Therefore, the operation rod 75 is operatedtoward the right in the drawing via the push-pull cable 78 whilecompressing the coil spring 76, whereby the coil spring 76 iscompressed.

When the transmission 3 is brought into engagement with a gear positionthat corresponds to the traveling speed of the vehicle at step S5, thecontrol means 10 proceeds to step S6 and de-energizes (turns off) theelectromagnetic solenoid 9 (SOL). As a result, the operation member 74is liberated from being limited, and moves toward the right in thedrawing due to the force of the coil spring 76 that has been compressed.Due to the engaging action of the inclined operation surface 741 of theoperation member 74 and the inclined to-be-operated surface 712 of theengaging member 71, therefore, the engaging member 71 moves down in thedrawing against the spring force of the coil spring 73, and the teeth711 formed at the lower end of the engaging member 71 are brought intoengagement with the parking gear 6. Thus, by temporarily limiting themovement of the operation member 74 by operating the electromagneticsolenoid 9, the transmission 3 can be reliably brought into engagementwith a gear position that corresponds to the traveling speed of thevehicle prior to locking the parking gear 6 or the input shaft 31 of thetransmission 3 even when the change lever 77 is quickly operated to theparking position (P). When the vehicle is brought into a halt,therefore, the transmission 3 is brought into engagement with any one ofthe gear positions, the input shaft 31 is locked, the wheels (not shown)transmission-coupled to the output shaft 33 of the transmission arelimited from rotating, and the parking state is established.

In the illustrated embodiment, the device is provided with theelectromagnetic solenoid 9 (SOL) as the parking lock limiting means. Theelectromagnetic solenoid 9 (SOL), however, needs not necessarily beprovided. That is, the parking operation detection means 85 (SW5) isprovided in the operation passage on the way to the parking position (P)of the change lever 77 and hence, the control means 10 executes thespeed-change control based on a detection signal from the parkingoperation detection means 85 (SW5). Therefore, unless the change lever77 is operated to the parking position (P) at a considerably high speed,the transmission 3 can be reliably brought into engagement with a gearposition that corresponds to the traveling speed of the vehicle beforethe input shaft 31 is locked by the parking lock mechanism 7.

Next, described below is a case where the change lever 77 has anoperation pattern shown in FIG. 3, i.e., where the reverse position (R)exists between the neutral position (N) and the parking position (P).

In the case of the operation pattern shown in FIG. 3, when the changelever 77 is operated from the neutral position (N) to the parkingposition (P) while the vehicle is traveling (moving forward), thecontrol means uses the detection signal from the reverse positiondetection means 83 (SW3) as a parking operation detection signal. Thatis, the change lever 77 is not operated to the parking position (P)while the vehicle is traveling (moving forward). In case a detectionsignal is input from the reverse position detection means 83 (SW3),therefore, the control means 10, usually, neglects it. In theillustrated embodiment, however, when the change lever 77 passes overthe reverse position (R) while the vehicle is traveling (movingforward), the control means 10 judges that the change lever 77 isoperated to the parking position (P), and executes steps S2 through S6in the flowchart of FIG. 2 described above.

The parking device of the present invention is constituted as describedabove. When the parking operation detection means has detected theoperation of the change lever, the control means sends a control signalto the speed-change actuator based on a detection signal from thevehicle speed sensor to bring the transmission into engagement with agear position that corresponds to the traveling speed of the vehicle.When the change lever is operated to the parking position (P) while thevehicle is traveling, therefore, the transmission can be reliablybrought into engagement with a gear position that corresponds to thetraveling speed of the vehicle before the input shaft of thetransmission is locked. When the vehicle is brought into a halt,therefore, the transmission is brought into engagement with any one ofthe gear positions and the input shaft thereof is placed in a lockedstate, the wheels transmission-coupled to the output shaft of thetransmission are limited from rotating, and the parking state isestablished.

1. A parking device for vehicles in which when an engine is brought into a halt, a clutch is disconnected and the revolution of an input shaft of a transmission cannot be controlled by frictional force of the engine, said parking device comprising a parking gear provided on said input shaft, a parking lock mechanism which selectively engages with said parking gear, a change lever which instructs a gear position of the transmission and is mechanically coupled to said parking lock mechanism, and a speed-change actuator for shifting the transmission to each gear position; wherein said parking device further comprises a neutral position detection means arranged at a neutral position of said change lever, a parking operation detection means arranged in an operation passage of said change lever from said neutral position to a parking position, a vehicle speed sensor for detecting a traveling speed of the vehicle, and a control means for controlling said speed-change actuator and said clutch based on detection signals from said neutral position detection means, said parking operation detection means and said vehicle speed sensor; and when the operation of said change lever is detected by said parking operation detection means, said control means sends a control signal to said speed-change actuator based on a detection signal from said vehicle speed sensor to bring said transmission into engagement with a gear position that corresponds to the traveling speed of the vehicle.
 2. A parking device for vehicles according to claim 1, wherein provision is further made of a limiting means for limiting the engagement of said parking lock mechanism with the parking gear, and said control means temporarily operates the limiting means based on a detection signal from said parking operation detection means when the operation of said change lever is confirmed. 